Surgery assistance systems have been known which assist a surgeon by synthesizing and displaying a three-dimensional tomographic image captured by an X-ray CT apparatus or the like prior to a surgery and an image showing the front end position and the like of a surgical instrument inserted in the body. To synthesize the two images, data processing is needed that changes sets of coordinate data serving as the bases of the two images into sets of data sharing the same coordinate system. Hereinafter, data processing for changing two sets of coordinate data into sets of data sharing the same coordinate system will be simply referred to as data alignment. For example, Patent literature 1 and 2 describe the present inventors' surgery assistance systems, and describe techniques in which alignment is performed between the three-dimensional surface shape data acquired by measurement using a three-dimensional surface shape scanner and the three-dimensional internal shape data (three-dimensional tomographic data) acquired in advance by measurement using a three-dimensional tomography scanner. Patent literature 1 and 2 also describe techniques in which marker parts for detecting position and posture, which are attached to a surgical instrument, are measured using the three-dimensional surface shape scanner to calculate the position and posture of the surgical instrument, and then alignment is performed between the three-dimensional surface shape data of the patient and the coordinate data of the front end position of the surgical instrument. These techniques enable alignment between the three-dimensional internal shape data and the coordinate data of the front end position of the surgical instrument.
Techniques in Patent literature 3 and 4 are some other conventional techniques describing the synthesizing and displaying of a three-dimensional tomographic image and an image showing a specific part of a surgical instrument inserted in the body.
Patent literature 3 describes a technique in which a surgery navigation apparatus displays the orientation of the optical axis of a currently-used rigid endoscope on a three-dimensional tomographic image.
Patent literature 4 describes a technique using an endoscope that has distance measurement means (such as a triangulation method using spot-light irradiation or an ultrasonic sensor) for measuring the distance from the front end of an inserted part of the endoscope inserted in the patient's body to a surgical site inside the patient's body. By the technique, a location the endoscope is observing is determined and displayed on a CT/MRI image captured prior to the surgery.
According to Patent literature 3 and 4 described above, a three-dimensional surface shape scanner is not used to acquire the three-dimensional surface shape data of the patient and the position and posture of the endoscope. Instead, markers such as light emitting devices are attached to the patient and the endoscope, and the coordinates of these markers are detected by a position sensor. In the system, however, it is necessary to acquire the three-dimensional tomographic image with the markers on the patient, and also to acquire the relationships between the markers attached to the patient and characteristic points on the patient's face. Thus, inconvenience may be caused to the patient, and the system may become complicated. In addition, the accuracy of the synthesis may be deteriorated if the positions of the markers attached to the patient are changed. Accordingly, the surgery assistance systems using a three-dimensional surface shape scanner as described in Patent literature 1 and 2 can be said to be superior in terms of simpleness and accuracy.
Patemt Literature
[Patent literature 1] J Publication of Unexamined Patent Application No. 2007-209531
[Patent literature 2] International Patent Application Publication No. WO2008/093517
[Patent literature 3] Publication of Unexamined Patent Application No. 2001-293006
[Patent literature 4] Publication of Unexamined Patent Application No. 2001-204738